Electrohydraulic brake for railway or like vehicles.



No. 676,745. Patented lune l8, mm. A. GOLDSBHMIDT.

ELECTROHYDRAULIG BRAKE FUR RAILWAY 0R LIKE VEHICLES. (Applicatiqn filedFeb. 19, 1901.)

(No Model.)

n: uonms versus 00., wow-urns. WASHINGTON, u. c.

, pipe connecting these two parts.

STATES Arnivr sures,

. ANDRE GOLDSOHMIDT, OFIARIS, FRANCE, ASSIGNOR TO COMPAGNIEINTERNATIONALE DU FREIN ELECTRO-HYDRAULIQUE DUREY, OF

BRUSSELS, BELGIUM.

ELECTROHYDRAULIC BRAKE FOR RAILWAY OR LIKE VEHICLES.

SPECIFICATION forming part of Letters Patent No. 676,745, dated June 18,190] I Application filed February 12, 1901. Serial No. 47,071. (Nomodel.)

To all whom it nuty concern.-

Be it known that I, ANDRE GOLDSCHMIDT, a subject of the King of Belgium,residing at 73 Rue Caumartin, Paris, in the Republic of France, haveinvented certain new and useful Improvements in Electrohydraulic Brakesfor Railway or Like Vehicles,of which the following is a full, clear,and exact specification.

The continuous and automatic electrohydraulic brake which forms thesubject of the present invention is an improvement on the ordinary typeof hydraulic brake controlled by electricity, in which the leverconnections which operate the brake-shoes are actuated by the activeforce of the vehicle in movement.

In American Patent No. 585,089, issued June 22, 1897, anelectrohydraulic brake was described working on the following principle:The active force of the vehicle in movement serves to automaticallymaintain a hydraulic accumulator arranged under each vehicle under ahigh and constant pressure, said accumulator being capable of beingbrought into communication with a brake-cylinder. In this system eachtime that itis desired to apply the brake communication is establishedby means of the electric operating mechanism between the accumulator andthe brakecylinder by opening a valve placed on the When it is requiredto maintain the brake in a certain braking position,this communicationis closed again after having been established, and the pressure createdis preserved by means of a spring arranged between the two piston-headsof the brakecylinder. In order to take off the brake, this spring mustbe completely relaxed and all the liquid which had served to produce itscompression forced into the reservoir. This system presents the twofollowing drawbacks: First, a somewhat slow removal of the braking,seeing that it is connected with a greateror lesser rapidity of theexpansion of the spring of the brake-cylinder, which is itself dependentupon the rapidity with which the liquid flows away behind the head ofthe internal piston of this cylinder, and, second, considerableconsumption of liquid under pressure, seeing that all the liquid whichhad served to produce a braking is returned without pressure into thereservoir which communicates with the atmosphere.

The result of this is the necessity of employing a powerful pump forequalizing the supply of liquid and rapidly reestablishing in theaccumulator the pressure necessary for a subquent application of-thebrake. This drawback-viz., the use of a powerful pump necessitating agreat expenditure of motive power-is particularly felt in the startingof a train after a more or less prolonged stoppage. In fact, the pumpfor charging the accumulator does not unprime itself automaticallyexcept at the moment when that high pressure is reached which it isdesired to maintain in the accumulator, and as at the start itfrequently happens that the pressure is low the necessary power for,establishing this pressure is borrowed from the axle of the vehicle,thus rendering more difficult the starting of the train.

My improved electrohydraulic brake entirely avoids the drawbacks which Ihave just pointed out.

For the sake of cle'arness I will now first describe the apparatus andits mode of working, and I will. then show how the construction andpeculiar arrangement of its parts enable the drawbacks hereinbeforeindicated to be avoided.

The accompanying drawing shows a sectional plan view of the apparatus.

Each of the vehicles of the train is provided with a similar apparatus,and the apparatuses are connected electrically by suitable couplings.The whole is operated by a single switch cl, placed within reach of thehand of the operator on the motor-car or engine. When running normallythe electric current circulates in all the distribution, actuating anelectromagnet governing the valves in such a way as to maintain thebrakes held off. The stoppage of the current, on the contrary, whetherproduced voluntarily by the action of the operator or whether it becaused by an accident-such, for instance, as the breakage of acoupling-gives rise to a movement of the said valves resulting in anapplication of the brakes.

The apparatus com prises a pump 6, the piston g of which is'connected byits rodfwith an eccentric or any other suitable means of transmissionmounted on the axle of the vehicle and constantly set in motion by thislat-.

' 19 above the compression-valve comm unioates with the compression-pipeproper, q, and also with a pipe 7", which communicates with the end ofthe pump-body behind the piston g, so that the valve is single-acting insuction and double-acting in compression. A valve 0., arranged on thepipe from the pump g, establishes or interrupts communication of thislatter with the reservoir 75, according as said valve is opened orclosed, such opening or closing being obtained by means of themanipulating-switch cl,causingthe passage or the suppression of thecurrent in an electromagnet 16. This electromagnet consists of a coil 8,the internal armature of which comprises a fixed parto and a movablepartw. This latter is subjected to the action of a spring g which tendsto force it out of the coil and to cause it to bear on the valve a, inthe form of a ball oranyothersuitablearrangement. l/Vhenthe currentpasses into the electromagnet, the movable core of x is drawn toward thefixed part 11, the valve a/is freed, and the liquid which thepump forcesback may return to the reservoir by the passage t, the chamber h, andthe passage c. When, on the contrary, the current is suppressed in theelectromagnets, the valve or rests on its seat, and so long as thevalves Z and at work freely the liquid forced by the piston g of thepump will lift a retaining-valve z and pass into the passage. Thislatter passage is terminated, on the one hand, by the front face of apiston 2 and, on the other hand, by a double valve 17 c. The valve 1),according as it is opened or closed, establishes or interruptscommunication betweenthe pipe 1 and the brake-cylinder 3, the piston 8of which actuates the brake-levers, and the valve a similarly, through apipe j, establishes or interrupts the communication between thecylinderand the reservoir 7c. The valve 0 may consist of a prolongationof a core 5 or movable'part of the armature of the electromagnet 4:,such core being drawn down by its own weight alone, its oppositeextremity acting on the valves 11. When the armature 5 is drawn up inconsequence of the passage of the current into the coil 4:, the valve Z)is closed and the valve 0 opened, and vice versa. The result is that thepassage of the current into the coil at causes the brake-cylinder tocommunicate with the reservoir by the body of the electromagnet and thepassage j, while the suppression of the current closes thiscommunication and causes the said cylinder to communicate with thepassage.

The piston 2, which is arranged in the cylindrical chamber h so that theaxis of its rod 7 is in the prolongation of the axis of the valves Z andm, is subjected on its rear face to the action of a powerful spring 6,which tends to move it away from the valves. It will thus be seen thatwhen the valve a is closed the liquid forced back by the piston g of thepump arriving in the passage will act on the front face of the piston 2and compress the spring 6. This spring is so regulated as to attain agiven tension at the moment when the rod 7 in rising encounters thesuctionvalve Z of the pump. At this moment the valves Z and m remainraised, and the retaining-valve continuing to be pressed on its seat theliquid drawn from the reservoir by the piston Q will return to saidreservoir, and the pump will work without resistance so long as thespring 6 preserves its tension. As the valve 1) is closed, (the valve 0consequently being open,) all the liquid which comes into the pipe 1will remain confined in this pipe and serve solely for compressing thespring 6 through the piston 2. If the valve 1) be opened, the liquidunder pressure contained in the pipe 1 will partly flow to thebrake-cylinder, forced by the piston 2 and the spring 6, which serves asan elastic and storing means for transmitting energy to the piston S foroperatingtheseries ofbrake-levers. Thebrakecylinder proper has nosprings. While the valve 1) is open the liquid reaches the brakedirectly from the back of the forcing-pump by the pipe 1, which forms acontinuous chamber betweenthe piston 8 of the brake-cylinder and thepiston 2.

The switch-handle d has four contacts-a central one 9, connected withthe positive pole, for instance, of a source of electricity 13, andthree contacts in the form of an arc' The handle of the switch mayassume the po-' sitions Lin which it is astride of two contacts 10 and11, II on the contact 10, III on the contact 11, and IV on the contact12. Under normal working the handle must be placed on the contact 10 inthe position II. In this position, which corresponds with the taking offof the brake, the current is suppressed in the electromagnet s, butpasses into the coil 4:, whereby the valve or is closed, the valve 1)The contact 10 is.

no longer absorbs energy.

isclosed, and the valve 0 opened. The valve '0 being opened and valve bclosed, the brake cylinder communicates with thereservoir,and

'uid drawn up by the passage t' until on the rise of the piston 2 therod 7 lifts the valves Z and m. At this moment the piston ceases toforce liquid into the pipe 1, but returns into the'reservoir 7t;all.,the liquid which it draws therefrom, and consequently the pump Inthe pipe .1, which is only separated from the brake-piston 8 by thevalve 12, there is thus in reserve a quantity of liquid at a pressurewhich cor responds to the tension of the spring 6. Now if it be desiredto apply the brake, the handle of the switch is brought into position IVon the dead contact 12. The current then passes into none of the coilsand the valve a is closed, the valve 1) opened, and the valve 0 isclosed, which means that communication between the brake-cylinder 3 andthe reservoir la is closed, while, the valve b.being open the piston 8is in communication with the pipe 1--that is to say, communication isestablished between this piston and the pressure of the pump on the onehand and the piston 2 on the other hand. Before the pump has need tocome into play the liquid under pressure available in the-pipe 1suffices for displacing the piston 8 in such a way as to bring thebrake-shoes in contact with the tires of the wheels. If the valve 1) isleft open, the pump continuing to force liquid into the pipe 1 willincrease the application of the brakes until the driver reestablishesthe current in the coil 4; but the limit of the braking will be alwaysattained when the spring 6, which forms, with the piston 2, an elasticstoring device for transmitting energy to the brake-engine, issufliciently compressed to allow the rod 7 to lift the valve l; but atany suitable moment, according to requirements, the drivercan stop theapplication of the brake or maintain it at the pressure which it hasreached by bringing the handle into the position III, which is aposition of strata quo on the contact 11. In this position the circuitis closed on the coil 8, the valve 0. being open, the valve 1) open, andthe valve 0 closed.

The retaining-valve z closes the communication between the pipe 1 andthe pump. The liquid drawn up by the piston of the latter returns to thereservoir, and the brakes remain applied with an energy which variesaccording to the degree of pressure of the liquid contained between thepiston 8, valve 2, and piston 2. If it be desired to increase thebrake-pressure, it suffices to increase the degree of pressure in thisliquid mass containedbetween the elastic part 2 and the brake-piston.For this object the handle is returned into the position IV, and thevalve a again closing a fresh quantity of liquid is admitted to the pipe1 and the pressure exerted on the working.

visable to prevent the pump from using up the energy of the vehicle durin g the first revolutions of the wheels of the train.

The arrangement which has just been described of the two valves a and b,the latter situated on the pipe 1 and the former on the communicationbetween the pump and the reservoir, enables the pump to be thrown out ofaction at any suitable moment, whatever maybe the pressure of the liquidin the pipe 1 at this moment and the corresponding position of thepiston 2. It suffices, in fact, to return, the handle into the positionI (starting position) astride ofthat is to say, in contact with-the twocontacts 10 and 11. The two coils s and a are then placed in circuit.The result is that valve to is opened, valve 1) closed, and valve 0opened. The pump then does not force liquid either into the pipe 1 orcylinder 3. It returns to the reservoir all the liquid which it drawstherefr0m,and its piston then works in consequence without absorbingother energy than what is due to friction.

It will be noted that to operate a removal of the brake the valve Z) isclosed, opening by the same action the valve 0. On the other hand allthe liquid under pressure contained in the pipe 1 and which serves formaintain ing the brakes applied remains in this pipe with its originalpressure. There is only discharged into the reservoir the quantity ofliquid under pressure which has penetrated into the cylinder 3 in frontof the valve i). On the other hand this valve now separates thebrake-cylinder from any elastic organ, and in order that the removal ofthe brakes may be operated and that the fall of pressure may be broughtabout it suffices to allow a single drop of liquid to escape into thereservoir. There is therefore an increase in the rapidity of the removalof the brakes and a considerable economy of liquid under pres sureobtained at each revolution of the brake, allowing of the iise of acompression-pump of smaller dimensions, and finally the starting of thetrains is facilitated by rendering it possible to throw out of actionthe pump by a simple movement of the handle of the switch.

I claim as my invention- 1. A continuous hydraulic electrically-operatedbrake in which the energy necessary for applying the brake is obtainedfrom a compression-pump actuated by the momentum of the vehicle,consisting of: a brakecylinder 3 communicating, by means of anelectrically-operated valve with the pressurepipe q of thecompression-pump through a pipe 1 on which is placed a retaining-valvesat the side of the pipe (1 and in a branch of which a piston 2 worksunder the pressure of a spring h, said piston and spring serving, duringthe application of the brake, as elastic organs for transmitting to thebrake-piston 8 the pressure of the liquid contained in the communicatingpipe 1, the greater part of this liquid under pressure remainingavailable in said chamber when the valve 1) is closed for taking of? thebrake, substantially as hereinbefore described and shown.

2. In an electrohydraulic brake such as de- 7 scribed, the combinationwith the communieating pipe 1 of an elastic mechanism for transmittingenergy, consisting of a piston 2, and a spring 71', so arranged that therod 7 of said piston 2 is situated in the prolongation of the axis ofthe valves Z and m of the compression-pump, and adapted to automaticallylift said valves to arrest the action of the pump when the liquid in thecommunicating pipe 1 has attained a given pressure, substantially ashereinbefore described and shown.

3. In an electrohydraulic brake such as dcscribed the combination withthe pressurepipe q, of the compression-pump, and at the rear of theretaining-valve ,2, of an electrically-operated discharge-valve acommunicating with the liquidrreservoir, and enabling .the operator toeffect a stoppage of the pump,

that is to say to cause it to work without absorbing energy, whatevermay be the pressure of the liquid contained in the communicating pipe 1between the pump and the brake-cylinder, substantially as hereinbeforedescribed and shown.

In witness whereof I have hereunto set my hand in presence of l'MLOwitnesses.

ANDRE GOLDSOI-IMIDT. Witnessesi EMILY BERT, EDWARD P. MACLEAN;

